1. Field of the Invention
The present invention relates to a device for alarming a stop setting error of a camera using an automatic stop uncontrollable lens during a flash photography under a TTL light emission control.
2. Related Background Art
Conventionally, an automatic stop controllable lens or an automatic stop uncontrollable lens has been used for a camera.
The automatic stop controllable lens has a correspondence between the position of a stop lever of the camera and the stop step number of the lens, while the automatic stop uncontrollable lens has no correspondence between the position of the stop lever and the stop step number. With a conventional camera, a discrimination between the automatic stop controllable lens and the automatic stop uncontrollable lens is made so that an automatic stop control of the uncontrollable lens is inhibited by the camera.
Of conventional cameras, there is known a camera of the type performing a flash photography under a TTL light emission control, wherein mounting of a stop controllable lens and a flash device is detected and setting of a stop control mode is detected, whereby a shutter speed is automatically set at a certain second suitable for the flash photography when mounting a flash device is detected, and the lens stop value is automatically controlled by the camera to set it at a value predetermined by the film sensitivity or the like.
In case where a flash photography under a TTL light emission control is performed using a camera mounted with a stop uncontrollable lens, it is common that a small stop diameter such as a minimum stop is set beforehand by the stop ring of the camera lens in a stop control mode. Therefore, a stop control of the stop uncontrollable lens is not effected by the camera and the stop remains unchanged to take the small stop diameter set by the stop ring.
Since the guide number (light emission quantity) of a flash device has a limit even with a flash photography under a TTL light emission control, there arises a problem of insufficient light quantity.